CHAPTER - 18
POLLUTIONOF AIR AND
WATER

AIR
• Air is a combination of different gases that form the atmosphere of
the Earth.
• The constituents of air are nitrogen (78%), oxygen (21%), water
vapour, carbon dioxide and other gases such as helium, ozone, argon
etc along with dust particles.
• Constituent of air may vary on other planets. However, some planets
do not have air. Space contains no air.

POLLUTION
Pollution is the introduction
of harmful or poisonous
substances into environment
that may cause adverse
effects.

1. AIR POLLUTION
It is the contamination of air,
which takes place due to
unwanted substances which
causes harmful effects on both
biotic and abiotic components.

AIR POLLUTANTS
• Any unwanted or harmful
substancepresent in the air that
decreases its quality and
contaminatesit is called air
pollutants.
• For example, smoke is an air
pollutant. Air pollutants can be
classified into different categories
based on their sources.
Pollutants are following :-
• Carbon monoxide
• Nitrogen oxide
• Sulphur Dioxide
• Hydrocarbons

How does Air Get Polluted?
• The substances which contaminate the air are called
air pollutants.
• Sometimes, such substances may come from natural
lsources like smoke and dust arising from forest fires
or volcanic eruptions.
• Pollutants are also added to the atmosphere by
certain human activities.

How does Air Get Polluted?
• The sources of air pollutants are factories , power
plants, automobile exhausts and burning of firewood
and dung cakes
• Many respiratory problems are
caused by air pollution.
Let us now try vto find out the substances or pollutants
which are present in the polluted air.

How does Air Get Polluted?
• Have you noticed how rapidly the number of vehicles is
increasing in our cities?
• Vehicles produce high levels of pollutants like carbon
monoxide, carbon dioxide, nitrogen oxides and smoke ..
• Carbon monoxide is produced from incomplete burning of fuels
such as petrol and diesel.
• It is a poisonous gas.
• It reduces the oxygen-carrying capacity of the blood.

How does Air Get Polluted?

How does Air Get Polluted?
• Boojho remembers seeing a thick fog-like layer in
the atmosphere, especially during winters.
• This is smog which is made up of smoke and fog.
• Smoke may contain oxides of nitrogen which
combine with other air pollutants and fog to form
smog.
• The smog causes breathing difficulties such as
asthma, cough and wheezing in children.

How does Air Get Polluted?
• Many industries are also responsible for causing air pollution.
• Petroleum refineries are a major source of gaseous pollutants
like sulphur dioxide and nitrogen dioxide.
• Sulphur dioxide is produced by combustion of fuels like coal in
power plants.
• It can cause respiratory problems, including permanent lung
damage. You have already studied about the burning of fossil
fuels in Chapter 5.

How does Air Get Polluted?
• Other kinds of pollutants are chlorofluorocarbons (CFCs)
which are used in refrigerators, air conditioners and aerosol
sprays.
• CFCs damage the ozone layer of the atmosphere.
• Recall that the ozone layer protects us from harmful
ultraviolet rays of the sun. Have you heard of the ozone hole?
Try to find out about it. Thankfully, less harmful chemicals
are now being used in place of CFCs.

How does Air Get Polluted?
• In addition to the above mentioned gases, automobiles which burn diesel
and petrol, also produce tiny particles which remain suspended in air for
long periods (Fig. 18.3).
• They reduce visibility.
• When inhaled, they cause diseases.
• Such particles are also produced during industrial processes like steel
making and mining.
• Power plants give out tiny ash particles which also pollute the
atmosphere.

CAUSES OF
AIR POLLUTION
• Air pollutionfrom Natural
Sources: Sometimes forest fires or
volcanic eruptions can lead to the
release of an excess of smoke and dust
in the atmosphere.
• Burning of fossil fuels: Coal and
petroleum used in industries and
vehicles when burnt release harmful
substances in the air such as carbon
monoxide, nitrogen oxides and sulphur
dioxide.
• Exhaust from factories: Many industries
release harmful substances like carbon
dioxide, hydrocarbons and other
harmful chemicals in the air which
decrease its quality.

EFFECTS OF
AIR POLLUTION
• Many problems related to
respiratory system might be
caused due to air pollution.
• Oxygen carrying capacity of
blood reduces because of
improper burning of vehicle
fuels. As the vehicles emit
high levels of pollutants like
carbon monoxide, carbon
dioxide, nitrogen oxides and
smoke into atmosphere.

ACID RAIN
• Gases like Sulphur and nitrogen react with the
water vapour present in the environment to
form sulphuric acid and nitric acid.
• The acids drop down with rain water, making
the rain acidic. This is called acid rain. Acid rain
can be harmful for living beings and also for
non-living things.
• Acid rain corrodes the outer surface of
buildings. This has caused the Taj Mahal
becoming pale.

CASE STUDY OF
THE TAJ MAHAL
• One great example of the
harmful effects of air
pollution can be viewed on
the Taj Mahal, the most
famous and beautiful
tourist attraction of India.
• The air pollution in that
region has led to
decolourization of the
white marbles of the Taj
Mahal.

CASE STUDY OF THE TAJ MAHAL
• The Taj Mahal Over the past 2 decades, India’s most
famous tourist attraction, Taj Mahal located in Agra
(Fig. 18.4), has become a matter of concern.
• Experts have warned that pollutants in air are
discolouring its white marble. So, it is not only living
organisms that get affected by polluted air but non-
livingthings like buildings, monuments and statues
also get affected.

CASE STUDY OF THE TAJ MAHAL
• .The industries located in and around Agra like rubber processing,
automobile, chemicals and especially the Mathura oil refinery, have
been responsible for producing pollutants like sulphur dioxide and
nitrogen dioxide.
• TheseBgases react with the water vapour present in the atmosphere
to form sulphuric acid and nitric acid.
• The acids drop down with rain, making the rain acidic. This is called
acid rain. Acid rain corrodes the marble of the monument.
• The phenomenon is also called “Marble cancer”.
• Suspended particulate matter, such as the soot particles emitted by
Mathura oil refinery, has contributed towards the yellowing of the
marble.

CASE STUDY OF THE TAJ MAHAL
• Towards the yellowing of the marble.
• The Supreme Court has taken several steps to save
the Taj.
• It has ordered industries to switch to cleaner fuels
like CNG (Compressed Natural Gas) and LPG
(Liquefied Petroleum Gas).
• Moreover, the automobiles should switch over to
unleaded petrol in the Tajzone.
Discuss with your elders and see what they have to
say about the condition of the Taj, 20 or 30 years ago!

GREENHOUSE EFFECT
You know that the sun’s rays warm the earth’s
surface. A part of the radiation that falls on the
earth is absorbed by it and a part is reflected
back into space.
A part of the reflected radiation i trapped by
the atmosphere. The trapped radiations
further warm the earth. If you have seen a
greenhouse in a nursery or elsewhere, recall
that the sun’s heat is allowed to get in but is
not allowed to go out.

GREENHOUSE EFFECT
The trapped heat warms the green house.
The trapping of radiations by the earth’s
atmosphere is similar.
That is why it is called the greenhouse effect.
Without this process, life would not have been
possible on the earth.
But now it threatens life. Excess of CO2 in the air
is one of the gases responsible for this effect.

GREENHOUSE EFFECT
It is the trapping of radiations inside
the earth’s atmosphere. Along with
other gases, CO2 also gets trapped in
the atmosphere which is responsible
for Greenhouse Effect.

GREENHOUSE EFFECT
You know that CO2 is one of the
components of air. You have also studied
the role of carbon dioxide in plants.
But if there is excess of CO2 in the air, it
acts as a pollutant.

GLOBAL WARMING
On the one hand, CO2 is continuously being
released because of human activities. On the other
hand, area under forests is decreasing. Plants
utilise CO2bfrom the atmosphere for
photosynthesis,Bthereby decreasing the amount of
CO2 in the air.
Deforestation leads to an increase in the amount
of CO2 in the air because the number of trees
which consume CO2 is reduced.

GLOBAL WARMING
Human activities, thus, contribute to the
accumulation of CO2 in the atmosphere.
CO2 traps heat and does not allow it to
escape into space. As a result, the average
temperature of the earth’s atmosphere
is gradually increasing.
This is called global warming.

GLOBALWARMING
• Because of human activities
the amount of CO2 level has
increased in the atmosphere
which traps heat and does not
allow heat to escape into
space.
• As a result, the average
temperatureof the
earth’s atmosphereis
gradually increasing. This is
called global warming.

GLOBALWARMING
• Other gases like methane,
nitrous oxide and water
vapour also contribute
• Towards this effect. Like CO2
they are also called
greenhouse gases.

GLOBALWARMING
• Other gases like methane,
nitrous oxide and water
vapour also contribute
• Towards this effect. Like CO2
they are also called
greenhouse gases.

ACTIONS TO PREVENT
AIR POLLUTION
• Trees take up carbon dioxide and
release oxygen. So, planting more
number of trees will reduce the
amount of carbon dioxide
responsible for Greenhouse Effect.
• Avoid unnecessary usage of vehicles.
• Try using public transport more.
• Natural resources like solar energy,
tidal energy, etc. should be used.

2. WATERPOLLUTION

2. WATERPOLLUTION

2. WATERPOLLUTION

2. WATERPOLLUTION

2. WATERPOLLUTION

2. WATERPOLLUTION

2. WATERPOLLUTION

2. WATERPOLLUTION

2. WATERPOLLUTION

2. WATERPOLLUTION
• The addition of undesirable
and unwanted material in
water which makes water
harmful for biotic and
abiotic components is
called water pollution.
• The things which pollute
the water are known as
water pollutants. Example
includes washing of
clothes, industrial waste
from factories etc.

HOW WATER
GETS POLLUTED?
A case study of Ganga River
• Ganga is one of the most
significant rivers of India.
• People living in these regions are
dependent upon Ganga water for
their livelihood as well as for their
day-to-day needs.
• But it has been found that Ganga
is one of the 10 endangered rivers
of the world according to the
(WWF) World Wide Fund for
Nature.

EFFECTS OF
WATER POLLUTION
• The harmful chemicals like arsenic,
lead, etc. discharged by various
industries have lead to many bad
effects like impure water, acidity
changes in water, etc.
• The usage of pesticides and weedicides
in the field gets mixed with water
bodies during rainfall. Indeed, this
water seeps into ground and has
polluted ground water too.
• Various diseases like cholera, diarrhea,
jaundice etc. results from water
pollution.

ACTION POINTS TO PREVENT
WATERPOLLUTION:
• Some plans can be implementedfor polluted rivers
like Ganga Action Plan was launched in 1985 with the
aim of reducing pollution levels in river.
• Industries must treat the waste before discharging
them into waters.
• At household level, candle type filter can be used.
Moreover, water must be boiled for drinking as it kills
the germs inside the water.
• Chemical process like chlorination can be used for
treating water.
• Laws for industrial units should be strictly
implemented to stop the throwing of wastesin water.
• Proper sewage treatmentplan must be implemented.

EUTROPHICATION
• Eutrophication is the presence of an
excess of nutrients in the water,
especially stagnantwater.
• Eutrophication mainly occurs due to
the addition of chemicals in the water
bodies.
• As a result, a large number of algae and
other plants start growing in water.
• As they die, decomposers begin to rise
in the water. These decomposers take
up most of the oxygen of the water.
• Hence, the lack of oxygen leads to the
killing of aquatic animals in the water
body.

Potable Water
• Drinking water or the water that is fit for consumption and food
preparation is also called Potable water.
How is water purified?
• In order to prevent water pollution, water from households, industries
and other sources is treated in a sewage treatment plant and then it is
released in the water bodies.
• Also, water from the water bodies is treated before passing it on to the
households and other industries to ensure that it is fit for the usage.

ACTION
KEYS TO
PREVENT
WATER
POLLUTION
Industries should strictly adhere to the laws
and do not dispose untreated sewage water
into the rivers or any other water body
directly.
More water treatmentplants should be
established near the industrial areas.
We should save water as much as we can, for
example, we can make sure that there are no
leaking taps in the houses.

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